ON THE LYMPHATIC SYSTEM. ] 67 



that the salivary tube^ which is of the same structure as that 

 in the parotid^ passes through a short narrow nech with exactly 

 the same distinctive characters as in the parotid^ directly into the 

 much larger alveoli, the cubical cells lining the neck directly 

 changing into the transparent columnar mucous cells of the 

 alveoli. In various places tliis neck is of different length, but 

 according to its structure it is comparable, not to the interca- 

 lated or intermediary tube in the parotid, but to the neck of the 

 \ilivary tube only. The intralobular ducts or the salivary tubes 



3 the submaxillary of the dog would, then, differ from those of 

 the parotid in not possessing the intermediary part at all. 



A similar example, viz. the transition of the duct into the 

 alveoli of the gland through a neck is found in the pyloric glands 

 of the stomach. 



In the serous portions (see below) of the human submaxillary 

 gland the salivary tubes pass through a short nech into a long 

 thin branched intermediary part ; the structure of the neck and 

 of the intermediary part and the transition of this latter into the 

 alveoli, is exactly the same as in the parotid of the rabbit. As 

 for the mucous portion of this gland, i.e. the human sub- 

 maxillary, the condition is the same as in the submaxillary of the 

 dog, i.e. the salivary tubes pass through a short neck directly into 

 the alveoli. In the ape the salivary tube passes into a neck of 

 much greater length tlian either in the dog or man. After this 

 comes a long, thin-branched intermediary part of the same 

 structure, and the same relation to the alveoli as in the submax- 

 illary of man. 



In the rabbit there is an indication only of a nech, after which 

 follows a short and narrow intermediary part lined with flattened 

 elongated epithelial cells, directly passing into the columnar 

 secreting cells of the much larger alveoli. 



In the guinea-pig the presence of a nech is not distinct; there 

 is an intermediary part of various length and more or less 

 branched. 



(3) In the sublingual gland the conditions are these : — In the 

 dog the intralobular duct passes through a distinct nech directly 

 into the alveoli ; the neck is conspicuous by its small diameter, 

 this being smaller than either that of the duct or the alveoli ; it 

 is lined with a layer of polyhedral epithelial cells with small 

 crowded nuclei. These cells pass directly into the columnar cells 

 lining the alveoli. 



In the subhngualis of the rabbit the conditions as regards the 

 nech and the absence of the intermediary part are exactly the 

 same as in the submaxillary gland of the dog, the two glands, 

 viz. the sublingual gland of the rabbit and the submaxillary of 

 the dog, being similar in structure, as will he shown below. 



